- ANALYTICAL SERVICES
- PROCESS MINERALOGY
- MINERALS BENEFICIATION
- HYDROMETALLURGY
- Leaching
- Solid-Liquid Separation
- Precipitation
- Solvent Extraction
- Adsorption and Ion Exchange
- Electrochemistry
- Crystallization
- Pilot Plants
- THERMAL PROCESSING
- ENVIRONMENTAL SERVICES
- ENERGY AND FUEL SERVICES
- BIOTECHNOLOGY
- COMMINUTION
- PILOT PLANT AND OTHER SERVICES
ADSORPTION AND ION EXCHANGE
Adsorption on activated carbon is the most widely used method to recover gold from cyanide solutions. Hazen is experienced in all conventional methods of gold recovery in cyanide circuits and specializes in activated carbon adsorption technologies. Hazen can determine carbon loading, carbon stripping and regeneration, Merrill Crowe precipitation, and ion-exchange recovery of gold and silver from cyanide solutions and alternate lixiviants. Carbon-in-leach (CIL) options can be evaluated in batch and continuous operations. Hazen's continuous CIL circuit has been used to design six commercial operations and for feasibility studies of many other commercial properties.
Activated carbon adsorption has also been used to remove mercury and other metals from solutions and to clean organic impurities from aqueous feed and wastewater streams. Other adsorbants, such as clays, aluminas, and zeolites, have been used for impurity removal.
Ion exchange resins are widely used for cleaning impurities from aqueous streams and have found application in some commercial metal recovery circuits. Hazen has generated the design criteria for many commercial operations using both cationic and anionic resins. Some examples include cyanide removal from wastewater, gold recovery from cyanide solutions, and removal of impurities from process streams.